This invention relates generally to computer system software authentication techniques, and more specifically, to such techniques for authenticating video game software cartridges.
Videographics computer game systems are well known, popular consumer products. A typical system includes a console that connects to an ordinary television set for displaying images of the game. The console receives controlling game software from a read only memory (ROM) that is usually packaged in the form of a cartridge. The cartridge is removably plugged into the game console. Some pointing device, such as a joystick, is also connected with the game console in order to allow the player to input positional information that is used by the controlling software to execute playing of the game.
An example of such a system is one manufactured by The Nintendo Co., Ltd., of Kyoto, Japan and widely distributed in many countries including the United States. The Nintendo brand videographics game system includes cooperating security circuits in the console and in the cartridge as a means to restrict the ROM cartridges that can be used with the game system to those authorized by the Nintendo company. U.S. Pat. No. 4,799,635 - Nakagawa (1989) of the Nintendo Co. is directed to such an authentication technique. Software controlled microprocessors exist in each of the game unit and the cartridge for executing related algorithms whose results are then compared. When a game cartridge is inserted into the console, a satisfactory comparison must be made before the game unit will accept and operate with the cartridge. This approach is rather complicated and adds to the cost of manufacturing the cartridge.
Therefore, it is the primary object of the present invention to provide a simpler security circuit for a ROM game cartridge that causes such a host game console to accept the cartridge and execute the game in accordance with the software stored in it.